---
id: CVE-2026-110872
title: >-
  Nodemailer from 3.0.0 before 10.0.10 contains a quadratic complexity denial of
  service vulnerability in the SMTP client reply parser in
  SMTPConnection._onData and isPartialResponse
summary: >-
  Nodemailer from 3.0.0 before 10.0.10 contains a quadratic complexity denial of
  service vulnerability in the SMTP client reply parser in
  SMTPConnection._onData and isPartialResponse. A malicious SMTP server or
  on-path attacker can stream …
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-400
  - CWE-1322
vendor: nodemailer
product: nodemailer
affected:
  - nodemailer >= 3.0.0 < 10.0.10
published: '2026-10-14'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T18:14:51.460'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-110872'
references:
  - url: >-
      https://github.com/nodemailer/nodemailer/security/advisories/GHSA-4g23-2xm8-66gc
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/nodemailer-3.0.0-before-10.0.10-denial-of-service-via-smtp-reply-parsing
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/nodemailer/nodemailer/security/advisories/GHSA-4g23-2xm8-66gc
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-110872.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-110872'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2552972'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-110872'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-110872'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
epss: 0.00355
epssPercentile: 0.28996
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-15T13:29:48.697322Z'
ingestedAt: '2026-10-15T00:02:07.190Z'
---

## Overview

Nodemailer from 3.0.0 before 10.0.10 contains a quadratic complexity denial of service vulnerability in the SMTP client reply parser in SMTPConnection._onData and isPartialResponse. A malicious SMTP server or on-path attacker can stream continuation lines without a completion line before authentication, blocking the Node.js event loop and exhausting memory.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Developer Hub, Red Hat Enterprise Linux 10, Self-service automation portal 2 · no fix planned: Red Hat Developer Hub, Red Hat Enterprise Linux 10, Self-service automation portal 2 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-110872.json)